1. Field of Invention
This invention relates to dynamic frequency hopping.
2. Description of Related Art
Frequency hopping patterns are used in wireless communications to take advantage of interference averaging effects obtained by changing frequencies when transmitting a block of data. Conventionally, frequency hopping patterns have been selected in a random matter. However, with increasing popularity of wireless systems such as cellular phones or personal digital assistance (PDAs), greater efficiency in resource utilization is required than provided by random frequency hopping. Thus, new technology is needed to increase resource utilization efficiency.
This invention provides a dynamic frequency hopping system that utilizes information from multiple base stations to optimize an estimated performance of each individual link, of all links supported by a single base station or of all currently active links supported by the complete communication system. The system assigns frequency hopping patterns based on current interference and traffic environments to avoid interference thus gaining the benefits of interference averaging and interference avoidance.
The system imposes less stringent measurement requirements on terminals (wireless mobile devices) because many measurement requirements are replaced by generating estimates based on measurement data received from other base stations within a base station neighborhood. A base station neighborhood of a first base station is a group of second base stations that may be affected by first links serviced by the first base station. The base station neighborhood may be defined by a link neighborhood. A link neighborhood of a link includes all other links whose interference to the link exceeds an interference threshold. Thus, any of the first links that is included in link neighborhoods of second links serviced by the second base stations may interfere with the second links. Therefore, the second base stations are included in the base station neighborhood of the first base station.
The dynamic frequency hopping system may continuously verify that the frequency hopping patterns assigned to the links of the system optimizes an estimated system performance. Each currently assigned frequency hopping pattern is compared against all other possible frequency hopping patterns that may be assigned to a particular link. A possible frequency hopping pattern that corresponds to a maximum possible estimated system performance is compared against a current estimated system performance corresponding to the current frequency hopping pattern. If the current estimated system performance is less than the maximum possible estimated system performance, then the frequency hopping pattern of the particular link is changed to the possible frequency hopping pattern to improve system performance.
When a request for a link is received by the dynamic frequency hopping system, a similar process as above is performed where the request is granted allocation of system resources and assigned a frequency hopping pattern if the total estimated system performance exceeds a performance threshold. If the performance threshold is not exceeded, then the request for a link may be either delayed or denied. In this way, the frequency hopping patterns of all the links of the system may be assigned so that an optimum system performance may be obtained.